Originally Posted by bjnicholson
The SQA are different than the normal class 15s. The gals at my LQS where I purchased it have said so. Believe, me I know how to wind a bobbin. I have rewound my bobbins for my SQA so many times I lost count. The only thing that helps me is a little (a 1/4" if that) piece of thick tape, right now I'm using the seam allowance tape, in the bottom of the bobbin casing. It seems to keep the bobbin from jumping around and I've had no problem with it since. Before that the darn thing would skip out of the guide and the thread was being fed off the front (towards you) instead of the back. Sounds crazy but it works for me.
the difference between a Class L bobbin and a Class 15 is hard to see at first. Ls are the same width as a 15, but not as high.
a Class L will "jump around" in a Janome because it doesn't fill the whole bobbin case. as we've read in the tips given here, you can use an L in a machine built for 15s, but once you've collected enough 15s, i'd recommend you gift the Ls to somebody whose machine was built for those.
most commercial prewounds are made using Class L bobbins. they don't normally have the little leader holes, either, so are nearly impossible to re-use.
when you shop for prewounds to use in a Janome it's very important to shop for only reusable Class 15s. if the vendor doesn't show a photo in which you can clearly see the little leader holes, and if it doesn't clearly state they are Class 15s then keep looking.
i have always had success with prewound bought here:
http://www.terradonembroidery.com/clear_quilt_15.htm